Chemical and heat resistant rubber composition

Abstract

A composition for use in piping and pump systems for elevated temperature, steam and certain chemical resistant applications of ethylene-propylene copolymer with peroxide generated carbon to carbon crosslinkage. Effective amounts of antioxidants, carbon black, lubricant, thermal stabilizer and aid to peroxide crosslinkage is added. An antioxidant and thermal stabilizer system is used to produce a product with unusual thermal stability characteristics. The composition may also have a mixture of high and low particle size carbon black which acts as an antioxidant and reinforcing system. The composition may also use very fine particle carbon black for a highly elastic application. The composition can be used for rubber components which are exposed to a high temperature or to certain chemical environments, or where unusually high elasticity is required.

What is claimed is: 
     
       1. An elastic and chemical resistant rubber composition comprising a peroxide crosslinked ethylene propylene copolymer; an effective amount of metal salts of dithiocarbamate; an effective amount of sterically hindered phenol; minor effective amounts of coagent to peroxide crosslinking; and carbon black of a particle size of about 13 nm to about 15 nm used in about 25 to about 100 parts per weight of copolymer. 
     
     
       2. An elastic and chemical resistant rubber composition of claim 1 wherein said peroxide crosslinked ethylene propylene copolymer is comprised of about 35% to about 45% ethylene and about 55% to about 65% propylene. 
     
     
       3. An elastic and chemical resistant rubber composition of claim 1 wherein said metal salts of dithiocarbamate are chosen from a group consisting essentially of nickel dimethyl-dithiocarbamate, nickel di-isobutyldithio-carbamate, bismuth dimethyldithiocarbamate, cadmium diamyldithiocarbamate, cadmium diethyl-dithiocarbamate, copper dimethyldithiocar-bamate, lead diamyldithiocarbamate, lead dimethyldithiocarbamate, selenium diethyl- dithiocarbamate, selenium dimethyl-dithiocarbamate, tellurium diethyl-dithiocarbamate, zinc diamyldithiocarbamate, zinc diethyldithiocarbamate, zinc dimethyl- dithiocarbamate, potassium dibutyldithiocarbamate, sodium dibutyldithiocarbamate, sodium cyclohexylethyl dithiocarbamate, zinc dibenzyldithiocarbamate. 
     
     
       4. An elastic and chemical resistant rubber composition of claim 1 wherein said sterically hindered phenol is tetrakis [methylene 3-(3',5'-di-tert-butyl. 4'-hydroxyphenyl) propionate] methane. 
     
     
       5. An elastic and chemical resistant rubber composition of claim 1 wherein said coagent to peroxide 
     
     
       crosslinking is N,N'-m-phenylene diamaleimide. 
     
     
       6. An elastic and chemical resistant rubber composition of claim 1 wherein said sterically hindered phenol is about 0.5 to about 8.0 parts per hundred weight of copolymer. 
     
     
       7. An elastic and chemical resistant rubber composition of claim 3 wherein said metal salts of dithiocarbamate are from about 1.0 to about 3.0 parts per hundred weight of copolymer. 
     
     
       8. An elastic and chemical resistant rubber composition of claim 1 wherein said coagent to crosslinking is about 0.5 to about 2.0 parts per hundred weight of copolymer. 
     
     
       9. An elastic and chemical resistant rubber composition of claim 1 including a metallic oxide. 
     
     
       10. An elastic and chemical resistant rubber composition of claim 9 wherein said metallic oxide is zinc oxide. 
     
     
       11. An elastic and chemical resistant rubber composition of claim 3 wherein said metal salts of diothiocarbamate are nickel dimethyldithiocarbamate in about 1.0 to about 3.0 parts per hundred weight of copolymer and nickel di-isobutyldithiocarbamate in about 1.0 to about 3.0 parts per hundred weight of copolymer. 
     
     
       12. An elastic and chemical resistant rubber composition of claim 1 including a lubricant process aid. 
     
     
       13. An accumulator diaphragm of the rubber composition of claim 1.